Source : Webster's Revised Unabridged Dictionary (1913)

Adulterate \A*dul"ter*ate\, v. t. [imp. & p. p. {Adulterated};
   p. pr. & vb. n. {Adulterating}.] [L. adulteratus, p. p. of
   adulterare, fr. adulter adulterer, prob. fr. ad + alter
   other, properly one who approaches another on account of
   unlawful love. Cf. {Advoutry}.]
   1. To defile by adultery. [Obs.] --Milton.

   2. To corrupt, debase, or make impure by an admixture of a
      foreign or a baser substance; as, to adulterate food,
      drink, drugs, coin, etc.

            The present war has . . . adulterated our tongue
            with strange words.                   --Spectator.

   Syn: To corrupt; defile; debase; contaminate; vitiate;
        sophisticate.

Source : WordNet®

adulterating
     adj : making impure or corrupt by adding extraneous materials;
           "the adulterating effect of extraneous materials" [syn:
            {adulterant}] [ant: {purifying}]